(a) Field of the Invention
The present invention relates to a scanning table assembly and, more particularly, to a scanning table assembly for use in a image-scanning system for imaging a document.
(b) Description of the Related Art
An imaging system in a scanner, a copying machine or a facsimile machine generally includes a scanning table assembly for scanning a document to obtain an image of the document, and a CCD unit. The scanning table assembly generally includes a full-speed scanning table extending in a main scanning direction and moving reciprocally in a sub-scanning direction, and a half-speed scanning table extending in the main scanning direction and moving reciprocally in the sub-scanning direction at a speed substantially half the speed of the full-speed scanning table.
The full-speed scanning table mounts thereon a light source for irradiating the document for scanning thereof and a single mirror for reflecting the light reflected from the document. The half-speed scanning table has a pair of mirrors for guiding the light reflected by the mirror mounted on the full-speed scanning table to be incident onto the CCD unit.
The full-speed scanning table is coupled to a pair of wires, driven by a drive mechanism, for tagging the full-speed scanning table along a pair of rails extending in the sub-scanning direction.
The half-speed scanning table moves so that the path length of the light reflected from the document is maintained at a constant. The half-speed scanning table is coupled to the full-speed scanning table via the wires.
The full-speed scanning table has four sliders slidably supported on the pair of rails, whereas each mirror is supported on the corresponding table at three points thereof so that the reflective surface of the mirror is easily adjusted for the angle of the reflective surface.
In the configuration as described above, it is liable that one of the four points of the full-speed scanning table or half-speed scanning table does not contact with the rail, with the remaining three points contact with the rails, whereby the table is in an unstable posture. This is especially true, if the pair of rails does not have an excellent planarity. The unstable posture of the scanning table causes vibration of the scanning table during the scanning movement thereof and degrades the image quality obtained by the image-scanning system.
For preventing the vibration of the scanning table, it may be considered sufficient that the rigidity of the full-speed scanning table be lowered to have some flexibility. However, such flexibility in fact lowers the accuracy of the angle of the reflective surface of the mirror, which is undesirable.
In view of the above it is an object of the present invention to provide a scanning table assembly for use in an imaging system, which is capable of affording an excellent image for the imaging system by preventing the vibration of the table.
The present invention provides a scanning table assembly in an imaging system including a full-speed scanning table having a light source for irradiating a document to be scanned and a first mirror for reflecting light reflected from the document, a half-speed scanning table having second and third mirrors for consecutively reflecting light reflected from the first mirror, the full-speed and half-speed scanning tables moving on a pair of rails in association with each other so that a path length of light reflected from the document toward a CCD unit is maintained substantially at a constant, at least one of the full-speed and half-speed scanning tables being supported at three points of the rails.
In accordance with the table assembly of the present invention, the three-point support configuration of the at least one of the scanning tables affords a stable posture of the scanning table so that an excellent image quality is obtained by the imaging system.
The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.